INET(3) Linux Programmer's Manual INET(3)
NAME
inet_aton, inet_addr, inet_network, inet_ntoa,
inet_makeaddr, inet_lnaof, inet_netof - Internet address
manipulation routines
SYNOPSIS#include<sys/socket.h>#include<netinet/in.h>#include<arpa/inet.h>intinet_aton(constchar*cp,structin_addr*inp);unsignedlongintinet_addr(constchar*cp);unsignedlongintinet_network(constchar*cp);char*inet_ntoa(structin_addrin);structin_addrinet_makeaddr(intnet,inthost);unsignedlongintinet_lnaof(structin_addrin);unsignedlongintinet_netof(structin_addrin);DESCRIPTIONinet_aton() converts the Internet host address cp from the
standard numbers-and-dots notation into binary data and
stores it in the structure that inp points to. inet_aton
returns nonzero if the address is valid, zero if not.
The inet_addr() function converts the Internet host
address cp from numbers-and-dots notation into binary data
in network byte order. If the input is invalid,
INADDR_NONE (usually -1) is returned. This is an obsolete
interface to inet_aton, described immediately above; it is
obsolete because -1 is a valid address (255.255.255.255),
and inet_aton provides a cleaner way to indicate error
return.
The inet_network() function extracts the network number in
host byte order from the address cp in numbers-and-dots
notation. If the input is invalid, -1 is returned.
The inet_ntoa() function converts the Internet host
address in given in network byte order to a string in
standard numbers-and-dots notation. The string is
returned in a statically allocated buffer, which subse-
quent calls will overwrite.
The inet_makeaddr() function makes an Internet host
address in network byte order by combining the network
number net with the local address host in network net,
both in local host byte order.
The inet_lnaof() function returns the local host address
part of the Internet address in. The local host address
is returned in local host byte order.
The inet_netof() function returns the network number part
of the Internet Address in. The network number is
returned in local host byte order.
The structure in_addr as used in inet_ntoa(),
inet_makeaddr(), inet_lnoaf() and inet_netof() is defined
in netinet/in.h as:
struct in_addr {
unsigned long int s_addr;
}
Note that on the i80x86 the host byte order is Least Sig-
nificant Byte first, whereas the network byte order, as
used on the Internet, is Most Significant Byte first.
CONFORMINGTO
BSD 4.3
SEEALSOgethostbyname(3), getnetent(3), hosts(5), networks(5)
BSD September 3, 1995 1